From: wroxdb Date: 2010-11-05T17:10:26+09:00 Subject: the second argument Hello, what's the argument of "obj" in: def []=(index,obj) ? I don't see it call this method with the second argument. Thanks The original code is: class Array2 < Array def [](index) if index>0 super(index-1) else raise IndexError end end def []=(index,obj) if index>0 super(index-1,obj) else raise IndexError end end end x = Array2.new x[1]=5 x[2]=3 x[0]=1 # Error x[-1]=1 # Error